The present invention relates to a forced-fusion fuse which when an abnormality has occurred due to short-circuiting of a wire harness within an automobile, a collision of automobiles, etc. compulsively interrupts the current between a power source and a respective load, and a circuit breaker that uses the forced-fusion fuse.
A conventional electrical system of an automobile uses a blade fuse or a large capacity fuse within a fuse box, thereby protecting a within-automobile wire harness when some abnormality or other has occurred in such wire harness or load (e g., power windows). A blade fuse and a large current fuse are fused when a large current has flown therein, As a result, the current between the battery and the wire harness in which an abnormality has occurred is interrupted, with the result that the wire harness or load is protected.
A large current fuse comprises a casing, first and second fuse terminals protruding from a lower end of the casing, a first connection plate within the casing that has been connected to the first fuse terminal, a second connection plate within the casing that has been connected to the second fuse terminal, a tin alloy on the first connection plate, and a fusion portion (or earth portion) connecting the first and second connection plates. A wire harness is connected to each of the fuse terminals. When the wire harness has been short-circuited whereby a large current has been caused to flow in the connection plate and a heat has been generated therein, the fusion portion is fused to thereby interrupt the current between the battery and the short-circuited wire harness. The tin alloy which is a low-melting-point metal is provided in correspondence with a rare short-circuiting and, by diffusion thereof, plays the role of causing the formation of an alloy layer on the fusion portion and thereby enlarging the resistance.